1 // Copyright 2012 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // This example demonstrates an integer heap built using the heap interface. 6 package heap_test 7 8 import ( 9 "container/heap" 10 "fmt" 11 ) 12 13 // An IntHeap is a min-heap of ints. 14 type IntHeap []int 15 16 func (h IntHeap) Len() int { return len(h) } 17 func (h IntHeap) Less(i, j int) bool { return h[i] < h[j] } 18 func (h IntHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] } 19 20 func (h *IntHeap) Push(x interface{}) { 21 // Push and Pop use pointer receivers because they modify the slice's length, 22 // not just its contents. 23 *h = append(*h, x.(int)) 24 } 25 26 func (h *IntHeap) Pop() interface{} { 27 old := *h 28 n := len(old) 29 x := old[n-1] 30 *h = old[0 : n-1] 31 return x 32 } 33 34 // This example inserts several ints into an IntHeap, checks the minimum, 35 // and removes them in order of priority. 36 func Example_intHeap() { 37 h := &IntHeap{2, 1, 5} 38 heap.Init(h) 39 heap.Push(h, 3) 40 fmt.Printf("minimum: %d\n", (*h)[0]) 41 for h.Len() > 0 { 42 fmt.Printf("%d ", heap.Pop(h)) 43 } 44 // Output: 45 // minimum: 1 46 // 1 2 3 5 47 } 48
